DEVELOPMENT OF THE POLYSTYRENE SCINTILLATOR TECHNOLOGY AND PARTICLE DETECTORS ON THEIR BASES VLADIMIR RYKALIN IHEP, PROTVINO INSTR-14, NOVOSIBIRSK, 24 FEBRUARY - 01 MARCH, 2014.

OUTLINE Scintillators produced by polymerization and by molding under pressure, detectors. New technology - melting of powdered polystyrene granules in mirror forms. Scintillating bars and strips. Scintillators with large sizes and thickness. Scintillators on the basis of scintillating granules, detectors. Thin scintillating counters on the basis of PMT ФЭУ-КC with linear extended photocathode.

IHEP POLYSTYRENE SCINTILLATOR FACILITY Just in 2000 the industrial extruder for production of scintillating bars and strips (WLS light collection) started working. Producing of scintillators at IHEP was began around 30 years ago. In an initial production stage the polymerized scintillators (polymerization of big blocks, machining) was mastered. Then the technology of extruding of bars and strips from length to 5 meters from big blocks of the scintillator was developed. High transparency of scintillators (2m at 10×200mm 2 cross section) allowed to use them in experiments at IHEP and CERN (DELFI, NA-12, DIRAC).

SCINTILLATORS PRODUCED BY MOLDING UNDER PRESSURE, DETECTORS Production of IHEP diecasting machines (scintillating plates and short bars) is the most demanded now. A number of the detectors on the basis of such plates are used in experiments at accelerators (electromagnetic and hadron calorimeters, guard systems) and for registration of cosmic particles (scintillating counters of the big sizes).

SCINTILLATORS PRODUCED BY MOLDING UNDER PRESSURE, DETECTORS Scintillating element of EM calorimeter (Shashlyk type) with WLS light collection. At IHEP it was designed the optimal configuration of that сalorimeters then they started being used widely. Scintillating element of large sizes counters with WLS light collection. Total number counters with square more 1×1 m 2 delivered in different Laboratories is around ,5 ton elements was used in guard systems. Typical photoelectron number for assembly of two plate (10mm thickness) is 40 ph.el./MeV.

COMMON VIEW OF CALORIMETER AND ITS ELEMENTS Sampling (1.5mm sci. - 0,275mm Pb) calorimeter of 110×110×650mm 3 sizes, energy resolution σ( E)/E=4%

DESIGN OF THE NEW TECHNOLOGY – THE MELTING OF POWDERED POLYSTYRENE GRANULES IN MIRROR FORMS. The construction of the mirror forms is very simple – a box with walls from mirror stainless. Around 1300 scintillating bars of 15×100×2000mm 3 and 10×60×2600mm 3 were delivered in European universities. At a use of 4 WLS Y-11 fibers of Ø 1mm photoelectron number from scintillator far ends was 10 and 13 respectively. More 1000 scintillating plates of 50×500×500mm 3 were delivered in Baksan neutrino observatory. Light output at length of light propagation 5 cm makes 90% from output of polystyrene polymerized scintillators, but the cost – in 3 times less.

The main parts of scintillating counter of 30×300×1500mm 3 on the base of PMT FEU-KC with photocathode of 15×200mm 2. To increase uniformity of light collection a соncentration of the scintillating adds was changed from center of the counter to its ends in a process of the melting. Number of photoelectrons (MIP) from ends of the counters was around 30. The MELTING OF POWDERED POLYSTYRENE GRANULES

Production power only one industrial set-up on production of polystyrene granules makes tens of thousands of tons/year. Scintillation adds don’t change technological process Scintillating granuls - scintillators for extra large experiments Granule counter of 20×200×200mm 3, one layer of WLS fiber with 10mm interval between fibers. Granul sizes are Ø3×3mm, density 0,65 g/cm 3 Polystyrene scintillator counter of 10×140×260mm 3. Measurements show that number of photoelectrons/MeV is around 40 for regular structure of polystyren scintillating granules and WLS fibers with 10 mm interval between fibers.

Thin scintillating counters on the base of PMT ФЭУ-КC with the extended linear photocathode Family of scintillating counters without light guide on the base of PMT ФЭУ-КС. Photoelectron number (from MIP) in the case of thin polystyrene scintillators of 1×200×200mm 3 and 0,5×100×100mm 3 sizes makes 20 and 12 respectively. PMT FEU-KC with photocathode of 15×200mm 3. Photocathode blue sensitivity is up to 70mA/W, Coefficient of multiplication – more 10 6

CONCLUSION – OUR PLANS 1.The increase of light attenuation of extruded, molded and melted scintillator for the purpose of replacement too expensive polymerized polystyrene scintillators. 2.The study and optimization of scintillating granules and detectors on the basis of granules. 3.The development of “thin counters” for experiments at low energies and ion beams. 4.The increase of the radiation hardness of polystyrene scintillators.